From a furtive web search during a pub quiz, to a sneak peak at the answers during an exam, most of us have been guilty of cheating at some point.

And now, scientists believe they have discovered the reason why.

New US research suggests that higher levels of two hormones in our bodies, testosterone and cortisol, encourage cheating and other unethical behaviour.

Errant: Higher levels of two hormones in our bodies, testosterone and cortisol, encourages cheating and other unethical behaviour, new research suggests

Testosterone is the chemical responsible for sex drive and muscle growth in men, whilst cortisol, which is released during times of stress, is responsible for the accompanying 'fight-or-flight' sensation.

The study was carried at Harvard University and the University of Texas

Study co-author Robert Josephs, Professor of Psychology at the University of Texas, explained higher testosterone levels give a person the courage to cheat.

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Meanwhile those with higher levels of cortisol, because they are stressed, have more of a reason to cheat.

'Elevated testosterone decreases the fear of punishment while increasing sensitivity to reward.

Elevated cortisol is linked to an uncomfortable state of chronic stress that can be extremely debilitating.'

Furthermore, Professor Josephs and his team discovered that cheating lowers levels of cortisol and reduces emotional stress, suggesting that cheating is in itself a form of stress relief.

Professor Josephs added this has 'the unfortunate consequence of reinforcing the unethical behavior' - a cheater feels better afterwards, meaning more cheating is likely in the future.

Differences: In tests, people who were later revealed to have cheated had higher levels testosterone and cortisol in their saliva, while those who were honest had lower levels of of both chemicals

The scientists discovered these links by measuring chemical levels in 117 people before and after a maths test, for which participants were told more correct answers would earn them more money.

They were, however, allowed to mark their own tests before handing them in.

Those that were later revealed to have cheated had higher levels of both chemicals in their saliva, while those who were honest had lower levels of testosterone and cortisol.

This suggests that reducing the levels of testosterone and cortisol in the body may reduce the likelihood of cheating.

Earlier research has demonstrated that the effects of testosterone on performance can be eliminated by rewarding groups, rather than individuals.

To reduce cortisol levels, an individuals' level of stress must be reduced, which has long been demonstrated to be possible through techniques such as yoga, meditation and exercise.

Vicious circle: The researchers found that cheating lowers levels of cortisol and reduces emotional stress, suggesting that unethical behaviour is in itself a form of stress relief

Professor Josephs and his team believe the true cause of cheating may be more chemical than anything else, implying that some people, such as those suffering from high levels of stress, may be more prone to cheating.

'The take-home message from our studies is that appeals based on ethics and morality — the carrot approach — and those based on threats of punishment — the stick approach — may not be effective in preventing cheating.'

Schools and universities take a very strict approach to cheating in exams.

In 2013, almost 1400 GCSE and A Level students in the UK were deducted marks, while a further 498 faced being disqualified from an exam.

Additionally, almost 100 teachers also received penalties for helping their students to cheat. But this research suggests harsh responses such as this may be the wrong approach.